The present invention relates to a ink particle jetting device for a multi-nozzle ink jet printer.
In a multi-nozzle ink jet of the type using two charge values, ink particles which are not used for printing are charged. The charged ink particles are deflected perpendicularly to the direction of the jet while passing through a deflection field which is produced by deflecting electrodes and are collected by a gutter. On the other hand, the ink particles which are used for printing are not charged. Accordingly, these ink particles pass straightly through the deflection field and strike a recording medium thus recording a dot thereon.
The quality of a print formed by the ink particles depends on whether or not the accuracy in the printing position of inks drops is high. Therefore, it is essential that the nozzles have a high jet direction accuracy. Heretofore, in manufacturing a nozzle array having a high jet direction accuracy, a technique whereby a stainless steel plate is drilled with a small diameter drilling machine or a technique whereby a single crystal of silicon is drilled by etching it by photolithography has been extensively employed.
The former is advantageous in that a long nozzle array having a length substantially equal to the width of a recording sheet can be formed and the nozzles have a considerably uniform diameter. However, there is a drawback in that the jet direction accuracy is of the order of .+-.0.2.degree. and accordingly the deviation in printing position on the recording medium is relatively large, 70 .mu.m.
On the other hand, the latter technique is advantageous in that the jet direction accuracy is high because the holes are cut in a single crystal of silicon taking into account the crystal orientation thereof. A nozzle array in accordance with the second technique has been tested and found to have a jet direction accuracy of the order of .+-.0.06.degree. with a corresponding deviation on the recording medium of 20 .mu.m. The quality of a print made with this nozzle array is considerably high. However, it should be noted that the technique is nonetheless disadvantageous in that is is difficult to manufacture a long nozzle array.
wafers having a major diameter of about 100 mm have recently been manufactured using semiconductor techniques. Therefore, a nozzle array 100 mm in length can be manufactured from a wafer. However, it is difficult to form 800 nozzles with a density of eight nozzles/mm in a wafer with a major diameter of about 100 mm because it is necessary to make the accuracy in thickness of the wafer at least in the array direction higher than the dimensional accuracy (usually about 1 .mu.m) of the nozzle and it is difficult to polish a wafer having a diameter of 100 mm with an accuracy higher than the above-described accuracy. Futhermore, the manufacture of the nozzles from the wafer must be carried out using photolithography. However, it is practically impossible using presently- known techniques to achieve using photolithography an economical yield.